Velocity rate beyond "the norm" in algorithms does trigger at least a review. Beyond that, what exactly they look and and what they do with that info is a bigger mystery. No doubt that some good sellers get swept up in the big net, and eBay doesn't care, nor do they need to care - plenty more seller fish in the sea.
Re: where to sell - this site in time once Brick Classifieds launches, Bricklink, Brick Owl, and by all means give Amazon a try but realize that they, too, have their algorithms that can trip you up, so make sure you understand the rules in every direction.
Between your velocity and a pretty low feedback rating - 99.2% isn't good with 4000+ feedback - you probably had a lot of star dings and possibly a number of cases opened, etc.
eBay (and Amazon) are not forgiving environments. You need to protect your selling account very carefully, and that means under-promising and over-delivering to customers, it means accepting the occasional scammer as a cost of doing business instead of trying to die on every hill, it means not being late in shipping pretty much no matter what (have emergency plans in place), etc.
Good luck in the future - eBay's not the only place to sell, take the lessons from there and go succeed somewhere else - it's the best revenge.